When a centralized database server provides services to the outside by using a blockchain-type ledger, the ledger records relevant data records that related users need to store.
In practice, the centralized database server usually serves enterprise users. The enterprise users need to store data records related to different service attributes, e.g., sources of the data records, and users of the data records, and projects that the data records belong to, etc. Data records related to the same service attribute are usually stored in a scattered and disordered manner in the blockchain-type ledger. Therefore, it is inconvenient to perform status statistics analysis and query on the data records related to the same service attribute.
Based on this, a solution for creating an index related to a service attribute of a data record is needed for flexible data query.